Cathode-ray tube implosion guard with beeswax annular metal frame and metal band

ABSTRACT

An implosion resistant cathode-ray tube for television display employing a first metal band surrounding and secured to the envelope adjacent the screen and a second metal, preferably steel, band around the first band and subjected to a large tensile stress. The second band glides over the first and to equalize tension at the corners, a lubricant is applied between the bands to reduce function between the bands. As a lubricant, beeswax is preferred.

United States Patent 72] inventor Friedrich Kober Aachen, Germany [21]Appl. No. 721,486

[22] Filed Apr. 15, 1968 [45] Patented Apr. 6, 1971 [73] Assignee U. S.Philips Corporation New York, N.Y.

[32] Priority May 11, 1967 [33] Germany [54] CATHODE RAY TUBE IMPLOSIONGUARD WITH BEESWAX BETWEEN ANNULAR METAL FRAME AND METAL BAND 1 Claim, 3Drawing Figs.

52 U.S.Cl. l78/7.8, l78/7.9

[5l] InLCl. l-l0lj 29/82 [50] Field ofSearcli l78/7.8, 7.9

[56] References Cited UNITED STATES PATENTS 2,970,311 1/1961 Napoli eta1 l78/7.8 3,278,682 10/1966 Panis et al l78/7.8

Primary Examiner-Robert Segal Attorney-Frank R. Trifari ABSTRACT: Animplosion resistant cathode ray tube -for television display employing afirst metal band surrounding and secured to the envelope adjacent thescreen and a second metal, preferably steel, band around the first bandand subjected to a large tensile stress. The second hand glides over thefirst and to equalize tension at the corners, a lubricant is appliedbetween the bands to reduce function between the bands. As a lubricant,beeswax is preferred.

PATENTEU APR Glen 3573; 368

Fig.3

INVENTOR.

FRIEDRICH KOBER AG T CATHODE RAY TUBE IMPLOSION GUARD WITI-I BEESWAXBETWEEN ANNULAR METAL FRAME AND METAL BAND The invention relates to atelevision display tube having an implosion guard which consists of ametal ring which is stuck, for example, to the tube, and of at least onesteel band arranged around the ring and subjected to a large tensilestress.

As is known, television display tubes must be provided with an implosionguard which prevents'the glass body from being completely destroyed whenair suddenly penetrates into the tube. As is known, in such an implosionguard, annular frames of a corrosion-resistant sheet iron are used whichare provided with reinforming ribs and with lugs at the corners forsecuring the display tube in the cabinet of a receiver. These bands arepressed over the tube from the neck as far as the mould match line andare surrounded by at least one steel band subjected to a large tensilestress. I

Experiments have shown that the implosion guard of such televisiondisplay tubes is effective when annular frames and clamping bands areused and is based on the occurrence of force components directedapproximately along the diagonals. However, great difficulty wasinvolved in determining the pressure forces which were absolutelysufficient to prevent an implosion. The experiments for determiningthese forces at the comershave shown that these forces can be greatlydifferent at the separate corners of a'tube, since the clamping band,when stretched around the annular frame, is subjected to friction,especially at the areas at which the direction of the steel bandstrongly changes, i.e. at the' comers of a rectangular televisiondisplay tube.

The frictional forces are produced between the steel band and theannular frame or between separate steel bands if several juxtaposedsteel bands are stretched around the annular frame. The invention isbased on recognition of the fact that it is essential to provide thesteel bands on the annular frame so that the forces produced at theseparate corners of the display tube are the same. According to theinvention, this may be achieved by reducing the coefficients of frictionbetween the annular frame and the steel band or between the separatesteel bands. For this purpose, according to the invention, aconditioner, preferably beeswax, is applied between the metal bands, atleast near the corners of the display tube, i.e. at areas at which agreat frictional force is to be expected. With the use of two juxtaposedsteel bands, the conditioner may be applied both between these steelbands and between the lower steel band and the annular frame near thecorners. If the conditioner is applied in manner, the coefficient offriction at the critical points is reduced to such an extent that auniform distribution of force at the comers of the display tube I isobtained without the stretching machine sliding off along the bands.However, it is also recommendable to apply a conditioner to the innersides of the beginning and the end of a band sliding over each other andclamped by the stretching device, because the tensile force produced inthe band by the stretching device is a maximum when the friction betweenthe band and the stretching device is a maximum and that between thebeginning and the end of a band is a minimum.

Known steel bands are generally manufactured for packing applicationsand are lubricated with oil'in order to permit the bands to more readilysliding over each other and to reduce the coefficients of friction. Thisstep is sufficient for the normal packing applications, it is true,since it is not essential that a given pressure should be exerted on thecorners of a packed article; it is only important that the'packingshould be kept intact. As already stated, however, it is of majorimportance with the use of such steel bands for protecting televisiondisplay tubes from implosion that equal forces should be produced at theseparate comers of the tube and that these forces should lie withincertain limits during the stretching operation, for example, between 900and 1000 kgs/corner.

The present invention therefore has the advantage that the coefficientof friction between clamping band and annular frame or between band andband can be reduced to such extent that a uniform distribution of forcesover the four corners FIG. 2 shows on an enlarged scale a part with twocomers of a an approximately rectangular television display tube; and

FIG. 3 shows the comer of a television display tube of FIG. 1, theimplosion guard now consisting of an annular frame and two juxtaposedsteel bands.

Referring now to FIG. 1, reference numeral 1 denotes the televisiondisplay tube,'viewed from the screen side, over the periphery of whichis passed an annular frame 2 which is provided at its comers with lugs 3for securing the tube in the cabinet of a receiver and is surrounded bya steel-clamping band 4 (shown in dotted lines).

In FIG. 2, reference numeral 1 also denotes the television display tube,reference numeral 2 the annular frame,

reference numeral 3 the lug and reference numeral .4 the steelclampingband. This FIG. shows a television display tube the screen of which islocated on the front side of the cabinet of limited by transverse lines7 between the parts sliding with friction over each other, i.e. betweenthe annular frame 2 and the steel band 4 or between the annular frame 2,the steel band 4 and the steel band 6. These conditioners cause thecoefficients of friction between the various bands to be reduced to suchan extent that the bands can be pulled across the comers withoutdifficulty and that equal forces are produced at all the comers of thetelevision display tube.

The use of such conditioners also affords the advantage that the steelbands need not be pulled so tightly that they are liable to break.

I claim:

I. A cathode-ray tube for television display having a substantiallyrectangular window portion and a conical portion adjoining the windowportion,'an annular metal frame surrounding and secured to the conicalportion adjacent the juncture thereof with said window portion, a metalband under tensile stress surrounding the annular metal frame, and alubricant consisting of beeswax between the metal band and the metalframe to reduce the coefficient of friction therebetween whereby theband can be drawn over the frame and the distribution of force at thecomers is made uniform.

1. A cathode-ray tube for television display having a substantiallyrectangular window portion and a conical portion adjoining the windowportion, an annular metal frame surrounding and secured to the conicalportion adjacent the juncture thereof with said window portion, a metalband under tensile stress surrounding the annular metal frame, and alubricant consisting of beeswax between the metal band and the metalframe to reduce the coefficient of friction therebetween whereby theband can be drawn over the frame and the diStribution of force at thecorners is made uniform.